Now that awesome rug might look a little intimidating but basically once you replace yarn with old t-shirt you can crochet like almost anything and upcycle those t-shirts into whateva you want.

I chose to do a cup cozy for my Copco re-usable reusable to-go mug.
For some reason I took off the grip cozy the cup comes with and it's lost now. I still had pieces of t-shirt I used to make headbands and of course I still didn't want to throw those away so yeah. They were small pieces I just knotted together to keep the "yarn" going.